Vapor electric device



NV- 5, v1935- H. c. RENTscHLER AL 2,019,533

VAPOR'ELECTRIC DEVICE Filed Aug. 31, 1.9.53

Patented Nov. 5, 1935 PATENT OFFICE VAPOR ELECTRIC DEVICE Harvey ClaytonRentschler,

Donald E. Henry, Bloomeld, N. J., assignors East Orange, and

to Westinghouse Lamp Company, a corporation oi Pennsylvania AApplication August 31, i933, Serial No. 687,602

1o ons. (ci. 17e-122) u This invention relates t'o an electric dischargedevice and more particularly to such a device that is adapted to beemployed for illuminating purposes. More specifically the invention isan im- 5 provenient over the device disclosed in the copendingapplication of Harvey C. Rentschler and 'Donald E. Henry, whichapplication was led on.

August 30, 1933. bears Serial #687,391, and is f .assigned to the sameassignee as the present ap- -l 0 pliction.

An object of our invention is to provide an electric discharge device ofthe metal vapor type whose efficiency is higher than that of similardevices'o this character heretofore produced.

Another object of our invention is to provide a metal vapor lamp whosecontainer has a subn stance therein for rendering ineective deleteriousgases which may be evolved orotherwise con= tained therein.

Another object of our invention is to provide an improved electricdischarge device having indi rectly heated cathodes so arranged with anexpansion element' for increasing the mechanical properties of saiddevice during operation.

'l 25 Another object of our invention is to provide an electricdischarge device having an improved novel electrode structure therein.

A further object of our invention is to provide A. an electric dischargedevice which may be rely assembled and transported.

Another object of our invention is to 'provide an improved electrode.structure.

Other objects and advantages of our invention vwill be perceived fromthe following description and drawing wherein,

Figure 1 represents a view in elevation with some parts in cross sectionoi a discharge device embodying our invention.

Fig. 2 represents a cross sectional view oi one 40 ofgvthe'electrodesembodying our invention.

-Fig represents a cross sectional view taken onlineIIIT-m ofFig.1. Y

Referring to the drawing, our electric discharge device which ndsutility as an illuminating means comprises an elongated glass envelopele composed of boro-silicate glass resistantto sodium vapor; The ends ofthe envelope are in the form of outwardly extending presses li and l2 inwhich are Ahermetilcally sealed respective rigid leading-in conductorsi3 and it hich extend exteriorly and interiorly of said envelope.

f An insulating plug I5 having a recessed portion denlng a `shoulder anda central'opening through the depththereof is located in one end of acoated nickel hollow cylinder le, serving as an electrode,

The nickel cylinder has its ends uncoated, but that portion of thecylinder between said uncoated ends has a layer of good electronemitting material, such as oxides or carbonates of calcium, strontiumand barium. That portion of the con- 5 ductor i3 located adjacent theinner face of the end plug l5 is enlarged at i6' so that its crosssectional area is greater than that of the central opening of' saidplug. A similar plug il ts in the other end oi said electrode it, with arigid l0 conductor it extending through the central opening therein.

That portion oi the conductor it within the cylinder has an enlargedsection l@ bearing against the plug to prevent the conductor i8 from l5`being withdrawn through said central'opening.

A short nickel rod 2t is welded to the conductor i3 to preventlongitudinal movement of the plug with respect to the conductor i3. Anickel ring 2l is welded to the conductor i8 to prevent longi-l 20tudinal movement of the plug with respect to the conductor i8. An l.shaped conductor 22 has its short arm welded to the conductor it and itslong arm to the uncoated section'oi the nickel cylinder le. A pluralityof spaced light but rigid 25 nickel angles it are welded to the upperuncoated` section of the cylinder it and bear against the plug il] tofurther insure proper rm cooperation between the plug and cylinder. Ahelically coiled heater element 2d, adapted upon incandescence 30 toheat the. electron emitting material to such a temperature thatrequisite electron emission takes place therefrom is welded to the rodsit and it. The electrode Just described is located at one end `of theenvelope it. At the other end of 35 said envelope and symmetricallyarranged with respect to said electrode is another electrode alsocomprising a nickel cylinder 25 having its ends uncoated and the portionbetween said uncoated portions being coated with a good electron emis- 0sion material. A plurality oi?l plugs 2t and 2l like the plugs l5 andil, are located in the ends thereof. The conductor it and a shortconductor 2t respectively extend through the central opening in theplugs 2t and 2i. Each of these conductors 45 have enlarged sectionswithin the cylinder 25 which sections bear againet the respective plugs.

A ring or cross bar 29 is welded to the conductors ld and 28 outside ofthe plugs for maintaining the plugs in position. e A plurality of 50nickel angles iid bearagainst the plug 2t and are welded to theelectrode 25.`

An L shaped rod 3l is welded to the conductor llt and to the uncoatedsections of the electrode 25. A coiled lamentary heater, not shown, and55 similar to the heater 24 is welded to the rods I4 and 28 and islocated in the cylinder-25.

An element 32l for mechanical expansion and contraction purposes and forother mechanical purposes is welded to the rods I8 and 28. The element32vmay be composed of nickel or copper and is in the form of a helicallywound contraction spring for maintaining the parts in straight lineposition as shown.

Contained Within said envelope which is first completely evacuated is aquantity of rare gas,

. such as neon, argon, helium. When argon is employed, it is preferablyat a pressure of about 0.2 mm. of mercury. Together with the rare gas isa sumcient quantity of metal such as sodium, caesium, rubidium, zinc,cadmium or the like.

In the course of our experimentations with devices of this character wehave found that the efciency of devices employing oxide coatedelectrodes to be relatively low and generally not higher than about '22lumens per watt. The voltage drop in 'these lamps we have found to behigher than was expected. We have further ascertained that the voltagedrop depends upon the particular rare gas or combination of rare gasesemployed with the sodium as the atmos phere within the envelope.

The voltage drop is lowest when argon is employed, higher withneon-argon and still higher with neon. Our experiments disclose that thevoltage drop was lowest and about l2 volts when argon is employed andabout l5 to 17 volts when neon-argon is employed, depending, of course,somewhat upon the spacing between the electrodes and the gas pressure.-

We believe that theilow lamp emciency is due in part at least to adeleterious gas, such as a diatomic or triatomic gas contained thereinduring the operation of said devices. Gases of this character, as forexample carbon monoxide,

oxygenx and carbon dioxide are liberated fromthe electron emittingmaterial during bombardment thereof. When the oxides, such as barium,strontium and calcium are employed as the electron emitting means, theyare generally prepared by coating with carbonates of these elements thenickel cylinderv that is to serve as an electrode.

The coated cylinder is then subjected to ele- Vated temperatures wherebythe carbonates are dissociated into oxides .and carbon dioxide or carbonmonoxide, the latter pass oi as a gas. Even with the normal precautionstaken, we do A not believe that absolutely all of the carbonates havebeen converted into the oxides, but that there is some carbonate left inthe coating after the heat treatment. This heat treatment is carried outwith the parts all assembled and with the envelope connected to theexhaust pumps and maintained in a highly evacuated condition.

After the coating has been converted to an oxide, the envelope issealed. Some of the plum-atomic gases we believe are not entirelyexhausted from said envelope, but are probably tenaciously retained bythe inner wall of the envelope and the metallic parts contained therein.

During the operation of the device these gases may leave the envelopewall and the metal parts contained therein. iin addition due tobombardment of the thermionically active oxide there Vare gasesliberated therefrom. It is our opinion that probably part of theemission from a barium oxide containing coating is derived from bariumsuboxide and barium metal which might have been formed during thebreaking down of the carbonates. The residual carbonates contained insaid oxide coating and probably some -of the oxide are continuallybreaking down during the operation of the device to liberate carbonmonoxide, carbon dioxide and oxygen.k These gases are deleterious and,Vtherefore, adversely affect the emission and the nature of thedischarge. These gases poison the electron emitting coating to lower thequantity of emission that may be obtained therefrom. This poisoningaction will probably be less when the device is operated on directcurrent than when operated on alternating current since the peakvoltages when on alternating current are higher than the direct currentoperating voltage and inasmuch as some of vthis gas again disappears bybeing driven into'one or the other electrode. The degree of gasdisappearance in the electrodes is not the same Aand hence on A. C.operation this gas may partly be shuttled back and forth between theelectrodes thus leaving more free gas at any one time than if operatedon D. C. In addition the presence of these diatomic gases within theenvelope introm duces inelastic impacts between the electrons and theatmosphere within the envelope. f

In order to obviate the above difficulties we have provided a means forincreasing the efficiency of said device and this means we believerenders ineffective the deleterious gases that are present within saidenvelope. This means comprises an inverted metal cup 33 having aquantity of a clean up agent or getter, such as misch y metal, magnesiumor the like contained therein.

The -cup 33 together with its contents is welded or otherwise secured tothe conductor at a place below the cylinder it and has its open endfacing away from said cylinder it,

The getter material may be vaporiaed means of a high frequency coilenergization. The getter is deposited on to the end of the envelopeadjacent the press i i. The getterreacts chemically with the deleteriousgases to render the same ineiective during the operation of said device.After the getter is ashed in the lamp as heretofore described, we haveobserved that its eiiiciency may be as high as 29 to 33 lumens per watt.That is to say that the efficiency of 4a sodium vapor lamp is increasedat least 30% when misch metal or similar getter is employed.

A misch metal gutter in a sodium vapor lamp lowered the voltage drop sothat it was as low as 8 or 9 volts when argon was employed therewith,h

ll-13 volts when neomargon was employed therewith, and .l5-i7 volts whenneon was emf ployed therewith. The values are, of course, not' fixedbecause they depend somewhat on electrode spacing. Lower values may beobtained or the voltages may be somewhat raised by greater spacing. Insubstantially all cases the voltage drop is substantially uniform fordiierent lamps em.A

ploying the same atmosphere and electrode spacing.

The reason for the above-surprising results which we have obtained isdue to the fact that the diatomic gases that are contained within thedevice as originally prepared and/or evolved durn ing operation thereofare now rendered ineiective. No longer can they poison the electrodes orreduce the elasticity of impact between the electrons and the atmospherecontained in said envelope.

An evacuated double-walled open-ended chamber 34 surrounds said deviceso that the proper temperature may be maintained during operationthereof. The chamber 34 and the lamp may be supported by means of a stem35 having a are 36 oi' appreciable width and a press 31.

Wrapped around said stem and having a portion.

thereof resting upon the flare is an insulator band or ribbon 38 ofasbestos whose outermost lap frictionally bears against the chamber 34.Sealed in the press 31 are a plurality of rigid conductors 39, 40 and4|, which extend towards the envelope I0 and only the conductors 39 and40 extend exteriorly of said stem. The conductor 40 is welded to theconductor I3 and the conductors 39 and 4I respectively are welded torigid conductors 42 and 43 which extend along, but are out of contactwith the envelope I0 and are welded to the exterior portion of theconductor I4. These rigid conductors serve as electrical conductingmeans and supporting means for the lamp. i

Although our invention has been described with some particularity, it isto be limited only by the prior art.

What is claimed: l

1. An electric lamp comprising an envelope, an atmosphere of acondensable valkali metal vapor and a thermionically active meanstherein, means also within said envelope for rendering ineffective gasderived within .the space enclosed by said envelope which gas wouldnormally lower the eciency of said device when expressed in lumens perwatt, said means'having a low volatility characteristic preventing itsforming a deposit throughout the envelope which would obstruct thepassage therethrough of the generated light, said means having a higheractivity towards the deleterious gas than does said alkali metal vapor,said means having a low combining power with said alkali metal.

2. An electric lamp comprising an envelope, an atmosphere of acondensable alkali metal gas and an electrode therein, said electrodecomprising a metal base and a thermionically active oxide coating onsaid base and a getter therein for rendering ineffective by chemicalaction deleterious gas entering said atmosphere and which gas whennormally present therein lowers the luminous efliciency of said devicewhen expressed in lumens Der watt, said means having a low volatilitycharacteristic preventing its forming a deposit throughout the envelopewhich would obstruct the passage therethrough of the generated light,said means having a higher activity towards the deleterious gas thandoesfsaid alkali metal vapor, said means having a low combining powerwith said alkali metal.

3. An electric discharge device comprising an envelope, an atmosphere ofa condensable alkaliy r a low combining power with said alkali metal.

4. An electric discharge device comprising an envelope, an atmosphere ofa condensable alkali metal gas and an electrode therein, said electrodeincluding Aa metallic foundation anda thermionically active oxide onsaid foundation and means within said envelope for rendering ineffectiveplum-atomic gas liberated from said coating during operation of saiddevice and which gas when normally present would lower the lu- 5 metaland a thermionically active electrode there- 15.-

in, and misch metal within said device for increasing the luminouseiliciency of said device.-

when expressed in lumens per watt. 6. A lamp comprising an envelope, analkali metal, a rare inert gas and a thermionically ac- 20,

tive electrode therein, said electrode comprising a metallic base and anoxide coating, and means located within said envelope at one end thereoffor rendering ineffective a gas contained within said envelope which gasnormally would lower the luminous eiiiciency of said device whenexpressed in lumens per watt.

'1. An electric lamp comprising an envelope, an alkali metal, a rare gasand a plurality of electrodes therein, one of said electrodes having ametal base and an oxide coating thereon, and misch metal at one end ofsaid envelope for rendering ineffective gas evolved from said oxidecoating which would normally lower the luminous eiliclency of the devicewhen expressed in lumens per watt.

`8. An electric discharge device comprising an envelope, having a,plurality of presses, a plurality of electrodes in line and located insaid envelope, conductors sealed in said presses and extending into saidenvelope, heater elements in series and electrically connectedrespectively to said conductors, said electrodes surrounding saidelements and including thermionically active surfaces, said electrodesbeing electrically connected 45 to said conductors, a thermal barrier ateach end of said electrodes and a mechanical expansion and contractionelement connecting said heater elements.

9. An electric discharge device comprising an envelope having aplurality of presses, a conductor sealed in each press, insulatorshaving an v opening therein through which said conductorsl pass, heaterelements connected to said conductors, a coiled element connected tosaid heater elements, a metallic cylinder coated with a goodthermionically active material surrounding said heater Lelements andhaving their upper and lower ends respectively closed by saidinsulators, other insulators'closing the other ends of said cylinder. 6010. An electrode structure comprising a hollow body coated with a goodelectron emitting material, an insulating plug, having a shoulder,located at each end of said hollow body, a heater element within saidbody, conductors passing through openings in said insulators andconnected to said heater elements, means abutting an outer face of oneof said plugs and secured to said hollow body for preventing said plugfrom moving away from said hollow body. Y0 HARVEYCLAYTON RENTSCHLER..

DONALD E. HENRY.

